A roving frame can comprise a flyer region having at least one and usually two or more rows of flyers, each of which is associated with a spinning spindle at which a core or core sleeve can be disposed so that in the roving process, the yarn can be wound upon the core sleeves to form a full bobbin thereon.
Although not relevant to the present invention, the roving frame may be provided with a drafting frame fed with sliver from a can field and the system can be equipped with one or more spinning frames (especially ring spinning frames) a creel in which empty core sleeves can be stationed until they are transferred to the flyer region and into which the bobbins can be fed in a waiting position, and a track system connecting the waiting position, creel, flyer frames and spinning frames.
The full roving bobbins are thus delivered to ring spinning or other machines for the further steps in the production of yarn or thread.
The roving frame can be associated with a suspension carriage system including tracks or rails running from the waiting location into the flyer region and leading out of the flyer region to a waiting region or creel and then to the other machines with which the flyer frame may be associated. That track system, for example, can service a number of roving frames and a number of spinning machines. The empty core sleeves, hereinafter referred to simply as cores, and the full bobbins can be displaced on suspension carriage trains which can have a number of mutually-articulated supports or holders from which the empty cores or the cores fully wound with yarn (full bobbins) can be suspended. Such "carriages" can be articulated together to provide a train which can extend the full length of the row of flyers and can be referred to as a suspension carriage train. The "carriages" may have grippers at the respective holders which automatically engage the cores when the latter are thrust from below onto the holders and can automatically release the cores as part of a bobbin change process.
In a standard bobbin change process, for example, in a system in which the suspension carriage train is fed into the flyer region of the roving frame, the spindle rail can rise to transfer fully wound bobbins to the suspension carriage train, the suspension carriage train can advance to position empty core sleeves in line with the spindle and the spindle rail can rise again to capture the empty core sleeve from the suspension carriage train.
The suspension carriage train, which thus brought empty cores into the flyer region, can then leave with the fully wound bobbins. At a replacement station, the fully wound bobbins may be removed from the suspension carriage train and replaced by empty cores. There may be a station at which yarn residues may be removed from the empty cores.
Such systems are known and, since automatic operation of bobbin-change systems do depend upon having empty cores correctly mounted with the suspension carriage train at the appropriate location, no fully or partially wound cores on that train at the time it enters the flyer regions, and no omissions of such cores at positions of the suspension carriage trains which are supposed to have such cores, monitoring of the suspension carriage system for functional correctness of core and bobbin mounting is essential.
The flyer frame and suspension carriage train system has been described, inter alia, in U.S. Pat. No. 5,375,405 which corresponds to German patent document DE 42 29 296 A1.
The invention is particularly concerned with such monitoring and its starting point is a roving frame with a system for automatic replacement of full roving bobbins with cores (empty core sleeves) in an arrangement in which the full bobbins and the cores are carried by a suspension carriage train on a track or rail system through the flyers (see also German patent document DE 44 21 778 C2). The monitoring for functionally correct core and bobbin mounting here is intended to establish that the hangers of the train have properly received the full bobbins or are carrying the empty core sleeves or have transferred them before or after the bobbin change operation. The type of mounting can be determined and it is also possible with this system to recognize whether the mounted element is a core or a bobbin. Upon a failure, i.e. a deviation from the prescribed mounting, an error signal is generated.
While this system provides a basis for monitoring the correctness of the adjustment of cores or bobbins to the hangers, it cannot itself assure that prior to the initiation of the bobbin replacement operation, every full bobbin can be transferred to the correct hanger and every spindle will receive a core. Hence there have remained problems with respect to correction of errors which may be detected in even the earlier system.